|
Ok, Jerry
I had very limited exposure to what Everett was
doing, but my understanding was that the placement of the throttle plate
right next to the port was to cure the horrid low rpm idle problem with the
PP and did not necessarily have to do with throttle response.
If the injectors are far up stream from the port then it will take some time X
after you open the throttle plate (and assuming your manifold pressure sensor is
near the throttle plate/port) for the decrease in manifold pressure to be
registered by the sensor/cpu and correction made to the injector timing to
inject more fuel (admittedly short period of time), then the fuel must be
injected and flow down stream past the throttle plate and into the port,
compressed and fired.
That all takes time with the difference between
injectors close to port and far - driving the distance/time it takes for
the new fuel mixture to travel to the combustion chamber. A rough
calculation indicates that with an average intake
velocity of 150 fps and with injectors 2 feet from the intake port that it would
take approx 13 milliseconds, just for the fuel travel (not counting
sensing/computing time). At 6000 rpm the rotation time is 10 milliseconds,
therefore it is likely that one or two revs will not have the corrected fuel
mixture as they will sense the new throttle opening immediately as an increase
in manifold pressure (they don't wait on no computation) , but the new fuel
won't get there for approx 13 Ms or perhaps slightly more.
I believe you will find that the closeness of the
throttle plate to the port may have little effect on throttle response, if your
injectors are far up stream - but, like I said, with limited exposure to
what Everett was doing, I could certainly be wrong, but just though I would
throw it up for consideration.
Ed A
----- Original Message -----
Sent: Friday, January 21, 2005 12:28
PM
Subject: [FlyRotary] Re: Pport/cold side
injectors
> Ed, Having the throttle plate right at the port is supposed to take
> care of the throttle response. That is what Alan and Everett came
up
> with. It does make intuitive sense that starting might be
problem with
> the injectors some distance away. Jerry
> On
Friday, January 21, 2005, at 12:14 PM, Ed Anderson wrote:
>
>
> Jerry,
> >
> > Despite the seeming evidence of cold side
problems - its all relative.
> > On
> > one version of
my intake I had all four injectors 24" away from the
> >
intake
> > port. I had no problem flying with it or producing
power with my NA
> > turbo
> > block. In fact, it
seemed based on a smidgen of data that I might be
> > getting 1/2
gallon/hr better economy (not conclusively proven),
> > however,
the
> > downside I found were three fold:
> >
>
> 1. The throttle response was not to my taste - it would bog, if
the
> > throttle was opened too suddenly. Some may feel that you
shouldn't
> > need to
> > ask for that kind of response from
an aircraft engine - but, Scotty,
> > when I
> > want more
power - I WANT MORE POWER NOW!
> >
> > 2. Starting on
cold mornings were horrid, ran the battery down a
> > couple
of
> > times. Now, my "Plugs Up" installation might have
contributed to that
> > problem as the normal orientation any liquid
fuel will run down into
> > the
> > chamber where it might
stand a chance of turning into vapor (or
> > flooding the
> >
engine), whereas my fuel would have to be lifted vertically.
>
>
> > 3. It did appear that I could not lean out the engine
quite as much
> > without
> > it starting to stumble, it seem
to take approx 1/2 GPH fuel flow to
> > keep
> > that from
happening - might have been evidence of some distillation -
> >
but,
> > who knows, could have been something else like fuel wetting
out on the
> > walls. I know this seems in conflict with
point #2, but that's what
> > occurred.
> >
> > So I
went back to all four injectors less than 3" from the ports.
> >
However,
> > there was no reason why I could not have continued to fly
with that
> > set up -
> > except for personal
perferences. That rotary will do well even on
> > less
than
> > optimum configuration.
> >
> > Ed A
>
>
> >
> > ----- Original Message -----
> > From:
"Jerry Hey" <j-winddesigns@thegrid.net>
> > To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> > Sent: Friday, January 21, 2005 11:32 AM
> >
Subject: [FlyRotary] Re: Pport/cold side injectors
> >
>
>
> >> Ernest, that your analysis is impressive. I've just reread
it again.
> >> I'm committed to trying with the cold side
injectors but if it does
> >> not work, I will
understand why. The upside is that if they don't
> >> work we
can lay the idea to rest, accept hot side fuel as the
only
> >> way and work on making it safe through proper
shielding. This is
> >> one
> >> of the
"little" things us p porters have to work out. Thanks,
> >> Jerry
> >>
> >>
>
>>
> >>
> >> On Friday, January 21, 2005, at
11:04 AM, Ernest Christley wrote:
> >>
> >>> On
Fri, 2005-01-21 at 10:23, Ed Anderson wrote:
> >>>> Wow! Ok,
Ernest
> >>>>
> >>>> Certainly sounds
plausible that long runners would contribute to the
> >>>>
separation of the wheat and chaff. I wish I could remember what my
>
>>>> professors taught me in those long ago days. Perhaps if I had
day
> >>>> dreamed
> >>>> less and studied
harder......Nah!!!
> >>>>
> >>>
>
>>> I took only one other thing away from that class.
>
>>>
> >>> What has LEAD got to do with octane?
It's a metal. It doesn't burn.
> >>> Why would anyone put
it in their gas?
> >>>
> >>> Well, it turns out,
the light (less carbons per chain) molecules are
> >>> easier to
atomize (convert to a semi-gaseous state by spraying
> >>>
through
> >>> a
> >>> small orifice). If you
want a nice compact carberator/intake system,
> >>> you need lots
of those short chains. The down side is, those short
> >>>
chains don't have a lot of energy and tend to want to burn on there
>
>>> on
> >>> when exposed to the pressure inside a
cylinder. What you want is
> >>> something that will
atomize like the short chain, but burn smoothly
> >>>
like
> >>> the medium length ones.
> >>>
>
>>> Enter LEAD, stage right.
> >>>
> >>>
Lead has four bonding points. Mix some with your gas, and each
lead
> >>> atom will attach to one end of 4 different carbon
chains. Remember,
> >>> the
> >>> chain only
burns when the end is exposed to oxygen? Well, now one
>
>>> end
> >>> is locked down. If the fuel started
out as pure mixture of 4 carbon
> >>> chains, and you mixed just
the right amount of lead, you'll end up
> >>> with
>
>>> a batch of molecules shaped like a plus sign (+). Each arm of
the
> >>> plus
> >>> will be 4 chains long.
The oxygen can only get at the ends, so this
> >>> mixture will
burn like 100 Octane (ie, 100% Octane).
> >>>
>
>>> And my last point. Higher octane is not always better.
High octane
> >>> is
> >>> good for turbo
applications, because is has a slower burn rate. But
> >>>
you
> >>> want the burn to occur so that the maximum pressure is
in the chamber
> >>> at
> >>> the highest torque
point of the cylinder/rotor rotation. Not before
> >>>
and
> >>> not after. If you're running exceedingly high RPM
in a non-turbo
> >>> application, LOWER octane may actually
produce more power. In this
> >>> situation, the higher
octane stuff may still be burning well into the
> >>> exhaust
cylce.
> >>>
> >>> Now, I'm done. My brain
is empty.
> >>>
> >>>>>
Homepage: http://www.flyrotary.com/
>
>>>>> Archive: http://lancaironline.net/lists/flyrotary/List.html
> >>>
> >>
> >>
>
>>>> Homepage: http://www.flyrotary.com/
>
>>>> Archive: http://lancaironline.net/lists/flyrotary/List.html
> >
> >
> >
> >>>
Homepage: http://www.flyrotary.com/
>
>>> Archive: http://lancaironline.net/lists/flyrotary/List.html
> >
>
>
> >>
Homepage: http://www.flyrotary.com/
>
>> Archive: http://lancaironline.net/lists/flyrotary/List.html
>
|